Sahih Bukhari Volume 9, Book 87, Hadith 6905

حَدَّثَنَا صَدَقَةُ بْنُ الْفَضْلِ، أَخْبَرَنَا ابْنُ عُيَيْنَةَ، حَدَّثَنَا مُطَرِّفٌ، قَالَ سَمِعْتُ الشَّعْبِيَّ، قَالَ سَمِعْتُ أَبَا جُحَيْفَةَ، قَالَ سَأَلْتُ عَلِيًّا ـ رضى الله عنه ـ هَلْ عِنْدَكُمْ شَىْءٌ مَا لَيْسَ فِي الْقُرْآنِ وَقَالَ مَرَّةً مَا لَيْسَ عِنْدَ النَّاسِ فَقَالَ وَالَّذِي فَلَقَ الْحَبَّ وَبَرَأَ النَّسَمَةَ مَا عِنْدَنَا إِلاَّ مَا فِي الْقُرْآنِ، إِلاَّ فَهْمًا يُعْطَى رَجُلٌ فِي كِتَابِهِ، وَمَا فِي الصَّحِيفَةِ‏.‏ قُلْتُ وَمَا فِي الصَّحِيفَةِ قَالَ الْعَقْلُ، وَفِكَاكُ الأَسِيرِ، وَأَنْ لاَ يُقْتَلَ مُسْلِمٌ بِكَافِرٍ‏.

Narrated By Ash-Sha'bi : I heard Abu Juhaifa saying, "I asked 'Ali, 'Have you got any Divine literature apart from the Qur'an?' (Once he said... apart from what the people have?) 'Ali replied, 'By Him Who made the grain split (germinate) and created the soul, we have nothing except what is in the Qur'an and the ability (gift) of understanding Allah's Book which He may endow a man with and we have what is written in this paper.' I asked, 'What is written in this paper?' He replied, 'Al-'Aql (the regulation of Diya), about the ransom of captives, and the Judgment that a Muslim should not be killed in Qisas (equality in punishment) for killing a disbeliever.'"